1. Field of the Invention
The present invention relates to a swivel snap hook made of synthetic resin to be used for various kinds of bags, knapsacks and the like.
2. Description of the Related Art
A metallic swivel snap hook of this kind, which has been often used, requires a number of components. Therefore, a number of production steps are required, thereby raising its production cost. Further, such a swivel snap hook is difficult to color in a durable fashion. Thus, the swivel snap hook tends to have a poor appearance and is unsuitable for a traveler""s bag, a shoulder bag and the like. For the reason, the use of this kind of the swivel snap hook has been restricted to luxury goods. Therefore, instead of this kind of the metallic swivel snap hook, a swivel snap hook made of synthetic resin has been used in an increased number of fields. This swivel snap hook of synthetic resin ensures an excellent productivity, a low cost and a small weight.
An example of such a swivel snap hook of synthetic resin is disclosed in, for example, Japanese Patent Publication No. 5-7567. This swivel snap hook is comprised of a belt-connecting ring, on which an end of a belt is to be attached, a swivel-snap-hook main body extending therefrom via a base portion. The swivel-snap-hook main body has at its upper part an enlarged engaging head portion via a neck portion, and at its lower part a hook body in a shape of a hook and a stopper piece extended along an opening of the hook body. The enlarged portion is engaged with a central engaging hole portion of the belt-connecting ring so as to be rotatable, so that it is integrally joined with the belt-connecting ring.
In the swivel snap hook as disclosed in this publication, a gate-shaped main body of the belt-connecting ring and a connecting bar for connecting both leg portions of the gate-shaped main body and capable of rotating around its center line are molded together in a single process using a pair of molding dies, in such a manner that both axis ends of the connecting bar are fitted in the respective fitting holes of the both leg portions. Because the belt-connecting ring is molded in a single process, the swivel snap hook can be assembled by such a simple operation that the enlarged head portion of the swivel-snap-hook main body is only made to be pressed into the engaging hole portion formed in a center of the connecting bar during the molding. Therefore, the assembly work can be facilitated and the production cost can be reduced.
In the swivel snap hook as disclosed in this publication, however, the stopper piece is molded such that it is slightly apart from an outside face of a front end of the hook body as disclosed in this publication and after being molded, the stopper piece is deformed elastically so that it can be hooked by an inside engaging face at the front end of the hook body. Therefore, troublesomeness for that process still exist, with a result that the production cost is raised to some extent.
On the other hand, according to Japanese Patent Publication No. 4-35161 for example, a swivel-snap-hook main body is molded with a slight gap between a front-end outside engaging face of a stopper piece and a front-end inside engaging face of a hook body, in order to omit a step of deforming the stopper piece to bring it into contact with the inside engaging face at the front end of the hook body. However, if the swivel-snap-hook main body is molded such that the front-end outside engaging face of the stopper piece is closed to the front-end inside engaging face of the hook body, the opposing engaging faces may be fused to each other so as to be integrated with each other. Therefore, it is necessary to make said gap sufficient for avoiding such a fusion. However, this gap allows a mating ring member to be hooked by the hook body to be slipped out therefrom easily. To avoid this, according to the above-described publication, a rib-like protrusion is provided on the inside engaging face of the hook body opposing the front end of the stopper piece.
The hook body is preferably so designed that its depth is as small as possible within a size allowable for the ring member to be hooked by the hook body. However, even if it is intended to form the gap between the front-end outside engaging face of the stopper piece and the front-end inside engaging face of the hook body to its minimum size, the gap has such a size that does not generate a fusion of the engaging faces at the time of molding, so the depth of the hook body is required to be large to that extent, which is not desirable in terms of appearance.
The present invention has been achieved to solve the above-described problems. Therefore, an object of the invention is to provide a swivel snap hook of synthetic resin in which the length and the depth of a hook body can be set to the same extent as the conventional ones and which can be molded such that a front-end outside engaging face of a stopper piece is in contact with a front-end inside engaging face of the hook body.
The above-described object can be achieved effectively by the following aspects of the present invention.
Specifically, according to a first aspect of the present invention, there is provided a swivel snap hook of synthetic resin including: a hook body having a hook extended from a base portion of the hook body; and a stopper piece having a front-end outside engaging face to be engaged with a front-end inside engaging face of a curved portion of the hook body, the front-end outside engaging face being extended up to the front-end inside engaging face, the stopper piece being elastically deformable with respect to a base end thereof as a fulcrum, wherein the front-end inside engaging face of the curved portion has a protrusion having a minute protruding height and protruded toward the front-end inside engaging face of the stopper piece.
The base end of the stopper piece is preferred not to be elastically deformed directly, and has such a structure that the base end is not broken even if a strong external force is applied to some extent. On the other hand, although the hook body and a belt-connecting ring are different in design from the conventional ones, the structure, operation, and effect thereof are not different.
Although according to the prior art, the swivel snap hook is molded in such a state that the front end of the stopper piece is located outside the front end of the hook body and after the molding, the stopper piece is elastically deformed to make its front end elastically engage with the front-end inside engaging face of the hook body, as described above. According to the present invention, such an operation is not required, so that the productivity is enhanced and production cost can be reduced.
The feature of the present invention is to provide the front-end inside engaging face of the hook body with a protrusion having a minute protruding height so as to face the front-end outside engaging face of the stopper piece. Therefore, when the swivel-snap-hook main body is molded, the minute protrusion is integrally molded on the front-end inside engaging face of the hook body. Thus, even if the swivel snap hook is molded with the front-end outside engaging face of the mating stopper piece being close to the front-end inside engaging face of the hook body, both the engaging faces are not fused to each other. Consequently, it can be molded with the front-end outside engaging face of the stopper piece being close to the front-end inside engaging face of the hook body, while the depth of the hook body can be set to be substantially as small as the conventional ones.
If it is intended to form a molding cavity for the protrusion such that it communicates with a molding cavity for the front-end inside engaging face of the hook body and is slightly apart from the molding cavity for the front end of the stopper piece, high precision processing of the molding dies and the material of high toughness are required, with which the production cost may be affected to a large extent. Then, according to a second aspect of the present invention, a minute portion of a tip end of the protrusion is molded integrally with an opposing surface of the stopper piece.
That is, the molding die is constructed such that the molding cavity for the inside engaging face of the hook body communicates with the molding cavity for the front end of the stopper piece via the molding cavity for the protrusion. At this time, a communicating aisle between the molding cavity for the protrusion and the molding cavity for the front end of the stopper piece end is made to be as minute as a pin hole. Consequently, after the molding, the tip end of the protrusion communicates with the front end of the stopper piece in a minute connection. Then, because the connection is minute, it is broken easily at the time of a first use of a finished product after being molded. As a result, the front end of the stopper piece comes into a firm contact with the tip end of the protrusion, or there is only a minute gap therebetween, which never damages a function of the swivel snap hook.
According to the first aspect of the present invention, the protrusion having a minute protruding height is provided on the front-end inside engaging face of the hook body. According to the second aspect of the present invention, the protrusion is molded such that the tip end thereof is integrated with the front-end outside engaging face of the stopper piece at a minute portion like a pin hole. According to a third aspect of the present invention, there is provided a swivel snap hook of synthetic resin comprising: a hook body having a hook extended from a base portion of the hook body; and a stopper piece having a front-end outside engaging face to be engaged with a front-end inside engaging face of a curved portion of the hook body, the front-end outside engaging face being extended up to the front-end inside engaging face, the stopper piece being elastically deformable with respect to a base end thereof as a fulcrum, wherein the front-end outside engaging face of the stopper piece has a protrusion having a minute protruding height and protruded toward the front-end inside engaging face of the curved portion. Further, according to a fourth aspect of the present invention, a minute portion of a tip end of the protrusion on the front-end outside engaging face of the stopper piece is integrally molded with the front-end inside engaging face of the curved portion. The operations and effects of the third and fourth aspects of the present invention are substantially the same as the first and second aspects thereof.
According to a fifth aspect of the present invention, a rib-like protrusion is provided below the front-end inside engaging face of the curved portion of the hook body, the rib-like protrusion having an inside end face on an extension of a front-end inside face of the stopper piece.
If such a protrusion, which is minute, is provided on the front-end inside engaging face of the hook body, when an annular member hooked by the hook body is tried to be removed from the hook body, it is caught by the protrusion so that a user may feel uncomfortable. Further, if the inside end face of the rib-like protrusion is extended inward of the extension of the front end inside face of the stopper piece, the annular member is made to be floated off a bottom face of the hook body. As a result, even if the stopper piece is pushed inward to remove the annular member from the hook body, the annular member interferes with the stopper piece, so that it cannot be removed easily.
According to a sixth aspect of the present invention, a height of the rib-like protrusion is slightly shorter than a gap between the front end of the stopper piece and the bottom face of the hook body.
A section of the annular member to be hooked by the hook body may be various in shape, such as a circular section, a square section and a narrow rectangular section. In case where the section is a narrow rectangular one or a plate-shape, if the rib-like protrusion is low, the annular member invades in between the rib-like protrusion and the front end of the stopper piece, so that the stopper piece is difficult to elastically deform by pressing or the annular member may be caught by the front end of the stopper piece.
According to a seventh aspect of the present invention, the rib-like protrusion is connected to the protrusion having a minute protruding height and protruded from the inside engaging face of the curved portion. If the rib-like protrusion and the protrusion having the minute protruding height are connected together, when the annular member is hooked by the hook body or removed therefrom, the annular member can be moved smoothly into and out of the inside of the hook body.